Mojo bindings: merge the control messages of sending disconnect reason and notifying endpoint close…

mojo/public/interfaces/bindings/pipe_control_messages.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [JavaPackage="org.chromium.mojo.bindings.pipecontrol"]
 module mojo.pipe_control;
 
 // For each message pipe running user-defined interfaces, some control
 // functions are provided and used by the routers at both ends of the pipe, so
 // that they can coordinate to manage interface endpoints.
@@ skipping 11 matching lines @@
 struct RunOrClosePipeMessageParams {
   RunOrClosePipeInput input;
 };
 
 union RunOrClosePipeInput {
   PeerAssociatedEndpointClosedEvent peer_associated_endpoint_closed_event;
   AssociatedEndpointClosedBeforeSentEvent
       associated_endpoint_closed_before_sent_event;
 };
 
+// A user-defined reason about why the interface is disconnected.
+struct DisconnectReason {
+  uint32 custom_reason;
+  string description;
+};
+
 // An event to notify that an interface endpoint set up at the message sender
 // side has been closed.
 // 
-// This event is only used for associated interfaces. When a master interface
-// is closed, the message pipe is shutdown directly.
+// This event is omitted if the endpoint belongs to the master interface and
+// there is no disconnect reason specified.
 struct PeerAssociatedEndpointClosedEvent {
   // The interface ID.
   uint32 id;
+  DisconnectReason? disconnect_reason;
 };
 
 // An event to notify that an interface endpoint that is meant to be set up at
 // the message receiver side has been closed before sent over the message pipe.
 //
 // This event is only used for associated interfaces.
 struct AssociatedEndpointClosedBeforeSentEvent {
   // The interface ID.
   uint32 id;
 };